1. Field of the Invention
This invention relates to means for facilitating the transfer of large bulk items and loads and, in particular, a means which may be simply and removably adapted to a pallet, skid or the like upon which said items are commonly stored or placed for transport.
2. Description of the Prior Art
Present day warehousing and related storage of bulk items and loads commonly involves the placement of such upon a substantially flat platform for later transport. Such platforms are commonly denominated "shipping skids" or "pallets". Often it is desired to transport items only a short distance, to rearrange a warehouse's storage area or to move goods from storage to a loading dock or the like. A long distance journey on a truck, train, airplane, boat or combination therefore, may ensue in which the items remain unitized upon the original pallet. The utility of such a platform lies in its ability to unify a multitude of items, such as cartons, into a coherent, although bulky mass. Such a mass may be handled efficiently with the aid of standard transport equipment, such as fork lifts, where an unwieldy number of smaller units requires excessive man-hours of handling and, hence, excessive cost.
Another advantage of the use of such pallets lies in their generally standardized construction and design. An otherwise awkwardly shaped bulk item, when fixed to a pallet, gains a standardized base by which the pallet may be handled and transported.
Apparatus primarily utilized for the present-day transport of pallets and attached items include the well-known fork lift truck. These are small factory-based trucks with protruding lifting arms or forks at the front. The forks may engage a pallet with articles thereon to elevate the pallet from floor level and move the pallet with its load of articles thereon from one warehouse location to another. Often, the limited warehouse space availability makes the use of a fork lift truck disadvantageous. Like an ordinary powered wheeled vehicle, such a truck has a limited turning radius. Additionally, the fork lift mechanism, which makes the attached pallet an extension of the truck, exacerbates the warehouse's shortage of handling space. The frame of the truck absorbs additional warehouse floor space. Finally, a fork lift truck is often severely limited in the extend of load and size of pallet it can handle due to the stresses induced in its (cantilevered) protruding tongue portion.
A number of attempts have been made to design an efficient means for coping with the transport of heavy items normally stored within warehouses upon pallets or shipping skids. Included in these efforts have been a number of attempts to support the pallet by its corners, utilizing wheeled means. Such an apparatus makes more efficient use of the floor space of the warehouse than a fork lift truck and has the capability of handling larger loads than such a truck. The Johnson U.S. Pat. No. 2,572,348 shows a specially designed, portable pallet equipped with casters. The casters may be moved from a rest position, (pallet lying upon the ground) to a transport position (pallet raised above the floor, casters the sole contact with the floor) to allow the pallet to assume support and transport configurations. Additionally, each of the wheel or caster assemblies may be removed. However, the apparatus of Johnson may only be utilized in conjunction with his pallet of a special construction which includes such non-standard features as a plate-like mounting means for adapting the casters to the pallet.
Other patents which, like the Johnson patent, depend upon means for pivoting casters or wheels which are integrally attached to the support platform so as to raise or lower the platform relative to the ground or floor are disclosed in U.S. Pat. No. 459,365 of Linden and U.S. Pat. No. 2,446,518 of Arnold et al. Like the Johnson patent, these patents also disclose specially constructed, load supporting platforms. Similarly, the Pride U.S. Pat. No. 1,973,098 discloses a substitute for the conventional carrying skid commonly employed for loads requiring basal support. The Lee U.S. Pat. No. 3,633,774 discloses a load platform or sled with two sets of removable canister wheels for transporting. However, the system disclosed therein also requires a special lifting lever to raise the sled before the caster wheels can be inserted.
Systems incorporating self-contained, integrally constructed wheels are disclosed in the McMurry U.S. Pat. No. 2,877,981, the Denholm U.S. Pat. No. 2,917,317, the Long U.S. Pat. No. 3,213,993 and the Winger U.S. Pat. No. 2,774,609. The inclusion of transport wheels as integral components in a load support element undesirably increases the cost of that element and it is generally preferred to utilize low cost, conventional skids as load platform without integral wheel units.
The Neumayr U.S. Pat. No. 2,621,941 and the Anderson U.S. Pat. No. 2,487,508 both disclose load supporting structures mounted for transport on wheels or casters in which are incorporated hydraulic lifting mechanisms for raising or lowering the platform base relative to the wheels or the frame in which the wheels are mounted. However, again these load supporting apparatus are specially constructed arrangements which are not adapted, nor are they intended, for use in the manner of conventional shipping skids or pallets.
It is desirable to have a system which utilizes standard, conventional skids or pallets with arrangements for readily affixing or coupling wheels or casters thereto in a manner which thereafter permits the relative elevation of the skids with respect to the wheels so that the system thereafter may be transported on the wheels, and subsequently lowered at the point of destination so that the wheels may be readily removed and utilized in conjunction with another load-bearing skid or pallet.